Download PopBio 2012 Abstracts - Department of Evolutionary Biology and

PopBio 2012 Abstracts Oral Presentations Session One -­‐ Spatial Studies Keynote: Diane Srivastava What plants can tell us about animals: bromeliads and their aquatic food webs Food webs vary over space, but the causes of this variation are often poorly understood, in part because of the covariance between environment and space in much ecological data. I suggest that faunal food webs in water-­‐filled bromeliad plants can be particularly useful for untangling the roles of space, environment and organismal traits. Phytotelmbromeliads provide a standardised and highly replicated habitat that crosses biogeographic zones, covers the breadth of environmental gradients, and contains organisms as disparate as bacteria and frogs. This allows us to answer questions such as: Do biogeographic differences in the species pool affect the structure and functioning of food webs? What is the relative importance of environmental determinism versus stochastic colonization for food webs? Why do organisms differ in their response to space and environment? Merav Seifan Multiple trait response and disturbance characteristics – going beyond simple tradeoffs Understanding the role of disturbances in shaping communities is an unresolved topic. The dispute has two aspects: first, disturbances with different characteristics may have different effects on the ecosystem. Second, the particular changes depend on the species’ potential responses, which are the outcome of species-­‐specific traits. For simplicity, models often use a restricted species’ responses arsenal, in which competitive ability facilitates species success under benign conditions, while some ability to persist under disturbance serves as an alternative trait. This approach creates a gap between nature and theory. As a solution, we considered a set of four key traits, representing potential classes of species responses to different disturbance characteristics, and studied the response of all trait combinations. Model results were compared with field observations from sites affected by two natural disturbances – flooding (predictable, large scale) and mole activity (unpredictable, small scale). The most general insight emerging is that under unrestricted trait combinations both well-­‐known and novel tradeoffs (or trait combinations) emerge. Most importantly, species-­‐specific competitive ability was insufficient to explain differential species success: without disturbances, species required not only high competitive ability but also some escape mechanism. When disturbance was present, species success could not be predicted without knowing the disturbance characteristics. Success switched with decreasing disturbance predictability, from high disturbance tolerance combined with high competitive ability to high disturbance tolerance combined with long-­‐term seed dormancy. We suggest that many of the discrepancies between theory and observations will be solved by abandoning the traditional tradeoff approach and allowing more flexible trait combinations. Zdeněk Janovský Spatial variation in herbivore impact on plant fitness – Not populations but vegetation matters Herbivores are capable of considerable influencing the individual life histories of plants. We examined the spatial variation of impacts of different herbivore functional groups (invertebrate and vertebrate rosette feeding and stalk grazing; seed predation only in the second year) in 27 populations of Succisa pratensis, a wet meadow perennial. We followed individually approximately 2700 plants over two years. The vegetation at each site was recorded by means of four phytosociological relevés distributed evenly in the area with marked plant individuals (15 x 7 m on average). There was considerable variation in herbivore occurrence among the years, but generally the plants growing at wetter microsites suffered more from herbivory, especially from invertebrate rosette feeders. The same pattern emerged from our preliminary analyses of the effects of herbivory on mortality. These results may have important implications for definition of what is a site from the plant’s perspective. The logic “site equals population” may not always be a good approximation. 1
Dirk Nikolaus Karger Biogeographical and ecological drivers of beta diversity across spatial scales Understanding variation in biodiversity is a central and current question in ecological and biogeographical research. Recently, differences in species turnover (beta diversity) have been used to address a variety of question ranging from niche vs. neutral theory to island biogeography. The concept of beta diversity is, however, highly complex and drivers of beta diversity are poorly understood. To disentangle which factors (biogeographical or ecological in nature) are crucial in determining beta diversity at a given spatial scale, we investigated fern community composition along an ‘island-­‐size gradient’ as well as an ‘elevational gradient’ at two different scales in the Southeast-­‐Asian archipelago of the Philippines and Indonesia. The ‘island size gradient’ provided us with a broad variation of biogeographical factors across a broad geographical region, while the ‘elevational gradient’ in contrast varied stronger in ecological factors. This allows us to understand which factors, biogeographical or ecological, drive beta diversity at a given scale. We found that ecological factors drive beta diversity mainly at a local scale while biogeographical factors predominate at a regional scale. Christian Schwarzer Restricted adaptability of rare edge populations to environmental change A predicted effect of climate change on the range of plant species is a shift along climatic gradients to fit the species´ climatic niches. Especially processes that occur at the contracting range margins are in discussion: some theories assume the often small and genetically depauperated marginal populations as endangered, others consider them as a crucial gene pool containing adaptations to unfavourable climatic conditions. The European bog-­‐ecosystems harbor a distinctive plant community containing species that reach their southern range limit in Central Europe. Here, we present the results of a common-­‐garden experiment with five plant species sampled at 14 bogs along a latitudinal gradient of 1500 km ranging from Northern Germany to Northern Sweden. Populations were cultivated in monocultures and mixtures composed of individuals from the same origin and exposed to five different climate treatments for a period of 13 months. Although the common garden was located at the southern edge of the gradient, productivity of the mixtures increased from southern to northern origins. Surprisingly, simulated effects of climate change increased biomass production of the northern, but decreased productivity of the southern communities. However, monocultures of the individual species showed the opposite pattern, with increasing productivity from North to South. Additive partitioning of biodiversity effects revealed that the northern populations benefitted most from growing in communities. This was caused 1) by negative dominance effects acting in southern communities indicating increased competition and 2) by equally high complementarity effects in all communities indicating similar facilitative effects and niche complementarity. Jana Knappová Quantity is more than quality: Abundance in the landscape rather than species traits determines colonization success in grassland plants Dispersal limitation, i.e. the lack of available seeds resulting in suitable habitats staying unoccupied, is reported in many plant species based on seed addition experiments. However, these experiments cannot distinguish whether the failure of a species to colonize suitable habitat was due to its dispersal traits or due to low availability of seeds in the surrounding landscape. In our study, colonization ability is expressed as proportion of occupied abandoned fields, which are thought to be potential habitats for grassland species. Three distinct types of limitation were represented by three groups of traits: availability of seeds in the surrounding landscape (seed production and frequency in source grasslands), dispersal traits and habitat requirements and their relative effect on species frequency in abandoned fields was assessed using variance partitioning. Both cross-­‐species analysis and analysis of phylogenetically independent contrasts were performed leading to similar results. We showed that dispersal ability as well as habitat requirements of a species are of considerably lesser importance for successful colonization of abandoned fields by dry grasslands species than is availability of seeds in surrounding landscape. Colonization of abandoned fields by dry grassland species will thus be best enhanced by supporting populations of the species in their native sites. 2
Margarita Mürk Genetic insights into the enigmatic and extremely rare Dactylorhiza ruthei Coauthors: Sophie Nordström, Tatjana Oja, Tarmo Pikner, Sebastian Sczepanski, David Ståhlberg, and Mikael Hedrén Dactylorhiza ruthei is an allotetraploid marsh orchid that is considered to be extremely rare. According to current data, only a few populations remain in single locations in Estonia, Germany and Poland. The original population discovered by Gustaf R. Ruthe on Usedom island in Germany is extinct. The large geographic distance between the existing populations and the significant difference in morphology raises questions about their relationship and origin. In this study we examined plastid haplotypes, nuclear ITS and five nuclear microsatellite loci in two populations of D. ruthei: one from Peenemünde, Germany and the other from Puhtu, Estonia; and compared them to other diploid and tetraploid Dactylorhiza species collected from around the southern part of the Baltic Sea region. Our results show that the two populations of D. ruthei are genetically distinct. If the Peenemünde population is related to the now extinct original population, it is unlikely that the Puhtu population has any close relation to either of them. The Puhtu population has been affected much more strongly by introgression from other taxa than the Peenemünde population, possibly hybridizing with D. incarnata, D. maculata ssp. fuchsii and D. majalis ssp. baltica that grow nearby. Our results also suggest that the Puhtu population could be recently derived from one of the local allopolyploids like D. majalis ssp. baltica; it could also be possible that one or both of the D. ruthei populations are results of independant polyploidization events from local D. maculata s.l. and D. incarnata. Marina Semchenko Plants are most tolerant of competition with their common neighbours: the relationship between spatial patterns and competitive ability Previous studies have concluded that conspecific aggregation should benefit weak competitors and put stronger competitors at a disadvantage, thus promoting species coexistence. However, if competitive ability is viewed as a continuum between selfish and cooperative behaviour, it becomes evident that traits determining spatial patterns and competitive ability could co-­‐evolve, resulting in greater dispersal in stronger competitors and reduced competitive ability in spatially aggregated species. We combined data from a field survey of seven temperate grassland communities with the results of a common-­‐garden competition experiment encompassing 28 focal species. In the field survey, the species identity of the nearest neighbour was recorded for one hundred randomly chosen individuals of each focal species. In the competition experiment, each focal species was subjected to a gradient of neighbour density and two neighbour identity treatments: conspecifics or another species often encountered as the nearest neighbour in the field. We found that highly aggregated species performed poorly when competing with heterospecifics, while species that mostly encountered heterospecific neighbours exhibited greater competitive ability as measured by tolerance of heterospecifics. Our study demonstrates that viewing competitive ability in the context of evolutionary game theory can provide new insights into the long-­‐debated topic of mechanisms promoting species coexistence. Session Two -­‐ Adaptations to Global Change Keynote: Andy Gonzalez Adaptation in the Anthropocene: Is the pace of global environmental change too great? Global environmental change over the last century has been so rapid and distinct that some believe we have entered a new era known as the Anthropocene. Our best data suggest that current rates of population extinction are orders of magnitude above the background rate captured in the fossil record. This has given rise to concern that the rate of environmental change may have exceeded the capacity of populations to evolve and adapt. In many cases environmental change is so widespread and rapid that the individuals can neither accommodate to them physiologically nor migrate to a more favourable habitat. Extinction will ensue, unless the population adapts genetically through natural selection. According to theory whether evolution can rescue plant and animal populations depends upon several crucial variables: population size, the supply of genetic variation and the degree of maladaptation to the new environment. Surprisingly little is known about eco-­‐evolutionary dynamics of populations responding to rapid environmental change. We have tested the conditions that affect the probability of evolutionary rescue (ER) by using new high throughput techniques in experimental evolution. Using yeast (Saccharomyces cerevisiae) as a model organism we found that evolutionary rescue is possible, and that the recovery of the population may occur within twenty-­‐five generations. We found that the probability of ER is indeed predicted by population size. Most recently we found that spatial and temporal 3
environmental change interact to determine the probability of evolutionary rescue in metapopulations. We found that ER is fostered by dispersal between local populations connected in a network. We also found that populations embedded within connected metapopulations that have experienced relevant historical environmental change have a greater probability of recovering by evolutionary rescue after rapid environmental change. Our microcosms are incomplete models of populations occupying natural landscapes, where other processes such as interactions between species or between combinations of stressors also influence population dynamics. I will close with some directions for future research that I hope will encourage the merger of ecology and evolution required if we are to conserve Earth’s biodiversity during the Anthropocene. Relevant references: Bell, G. and Gonzalez, A. (2009) Evolutionary rescue can prevent extinction following environmental change. Ecology Letters 12: 942-­‐948. Bell, G. and Gonzalez, A. (2011) Adaptation and evolutionary rescue in metapopulations experiencing environmental deterioration. Science 332: 1327-­‐1329. Sabine Hänel Phenotypic response of annual plants to long-­‐term rain manipulation along a climate gradient Plant species that can not tolerate climate change are under the risk of extinction. Annual plants are capable of an immense plasticity, allowing them to deal with varying environments. In this study we aim to characterise phenotypic variation in response to changed precipitation. Climate change effects were simulated in a unique long-­‐term rain manipulation experiment which was conducted in a semi-­‐arid and a Mediterranean site in Israel. In the 9th year after starting the manipulation we studied the in situ response of 16 abundant annual plant species to the different precipitation levels. We measured life history traits such as growth and phenology along the growing season. We expected that a short growing season due to less precipitation will lead to a faster development to reproduction and that this is accompanied by decreased growth. Our findings contradicted this hypothesis. We detected an accelerated development in only 5 species, associated with faster growth in all cases. Most other species delayed onset of flowering and growth. Our findings point to the importance of a multi-­‐species and experimental approach to studying plastic response to climate change. Aud Halbritter Ruderal plant populations differ in their responses to latitudinal and elevational temperature gradients Declining temperatures along elevational and latitudinal gradients affect the distribution of many species. Interestingly, plants often reach colder low-­‐temperature limits along elevational gradients. This could be due to differences in the dispersal distances along the temperature gradients, which is greatly compressed along elevational gradients compared to latitudinal gradients. Alternatively, plants from high elevation and high latitude might differ in their genetic adaptation to low temperature and other environmental factors. To test these hypotheses, we performed a field survey along elevational and latitudinal gradients, and reciprocally transplanted 6 ruderal plant species from three origins (high elevation, high latitude, low elevation and latitude) to five different sites within and outside their present range along these gradients. After one growing season, plants performed generally better at high latitude than at high elevation suggesting that the longer photoperiod compensates for lower average temperatures at high latitude. Most species showed evidence for high plasticity rather than local adaptation, although populations of Plantago major from high elevations flowered earlier than populations from other origins. Our results indicate that caution is needed when using elevation as a proxy for latitude in studies of species distribution. Nonetheless comparative studies along such gradients can yield important insights into the factors that limit species distributions. In addition these findings might help understanding how plants at the range margin will react to changing climate conditions. Niek Scheepens Flowering phenology and reproductive fitness along a mountain slope: maladaptive responses to transplantation to a warmer climate Coauthor: Juerg Stoecklin Global warming has resulted in a longer growing season, leading to earlier flowering in various plant taxa. Elevational gradients are ideal to study the effects of global warming as they allow transplantation of plants from their original 4
occurrence down to elevations with a prospective climate. We performed a transplantation experiment with the perennial monocarpic herb Campanula thyrsoides L. from the European Alps and asked whether plastic adjustments in phenology might be compromised by current genetic adaptations of plants. Plants from ten populations were transplanted to three sites along a steep mountain slope (600, 1235 and 1850 m above sea level) to investigate the effect of the elevation treatment as well as origin effects on phenology, reproductive traits and fitness. We further investigated whether any origin effects in the investigated traits were due to local adaptation to climatic conditions of origin, and we investigated current selection pressures after transplantation. Our results showed that transplantation of Campanula thyrsoides to lower elevations caused strong shifts in phenology, with plants starting growth and flowering earlier, and ending their reproductive cycle earlier than at higher elevation. However, the shift in phenology came along with a high cost in fitness, indicating maladaptation. We conclude that the frequently reported phenological shift in plant species as a response to global warming may include heavy fitness costs that may hamper their survival in a warmer future. Sara Tomiolo How important are biotic interactions for local adaptation? Consequences for response of plants to climate change The response of plants to climate change is closely related to their degree of local adaptation to habitat conditions with loosely adapted populations having possibly a larger adaptive potential. Two major classes of ecological filters determine local adaptation in plants: abiotic stress (e.g. water availability) and biotic interactions, the latter of which has been widely ignored. Studies of plant-­‐plant interactions along environmental gradients indicate a trade off between competition and facilitation with decreasing water availability, i.e. adaptation to competition may be more important under benign conditions. In addition, plant-­‐soil interactions have not been treated in local adaptation studies, except for negative plant-­‐soil feedbacks. Therefore, we know virtually nothing about the role of biotic interactions as selective force relative to abiotic factors. Here we combined reciprocal sowing, neighbor removal and soil transplant along a rainfall gradient using populations from Mediterranean and Semi-­‐Arid ecosystems. We tested statistical interactions between planting site, seed and soil origin, and neighbor presence. Our results suggest that indeed, plant-­‐plant and plant-­‐soil interactions play a major role for determining plant performance, with complex interactions with species and climatic region. Therefore, biotic interactions must be addressed when studying local adaptation in the future. Esther Frei Testing adaptation and plasticity in plant populations under climate warming Coauthors: Philippe Matter, Thomas Hahn, Jaboury Ghazoul, and Andrea R. Pluess The local persistence of plant species under climate warming is largely mediated by adaptation and phenotypic plasticity. In species with a wide altitudinal range, plant population responses are likely to differ at contrasting elevations. We hypothesised that plants are adapted to their altitude of origin and that high elevation populations have greater phenotypic plasticity than low elevation populations as a consequence of habitat heterogeneity. In common gardens at 600m, 1200m and 1800m a.s.l we studied plant responses of low (1200m a.s.l.) and high (1800m a.s.l.) elevation populations of three grassland species (Ranunculus bulbosus, Trifolium montanum and Briza media). Given that soil depth decreases with increasing altitudes, we used deep, pure vs. shallow, stony soil conditions as additional treatment. Phenology of all three species was advanced at lower altitudes independent of the altitude of population origin or the soil treatment. Generally, performance was better in the pure soil treatment. In R. bulbosus, vegetative growth decreased while reproduction increased in the gardens at higher altitude. In T. montanum, growth differed between the altitudes of treatment while reproduction was highly variable within gardens and soil treatments. In B. media, plants grew similar at all altitudes of treatment but plant growth differed between the two altitudes of origin, however, without indications for adaptation to altitudes. Our tentative conclusion is that the study species seem not to be adapted to their altitude of origin. Variable growth in relation to environmental conditions indicates high phenotypic plasticity which might buffer plant species in a warmer world. Anne Rysavy Identifying key mechanisms influencing the fate of a common Mediterranean dwarf shrub under changing climate Coauthors: Merav Seifan, Marcelo Sternberg, and Katja Tielbörger Understanding and predicting the responses of plant communities to environmental changes and disturbances is one of the oldest challenges in ecology. As climate change continues to afflict natural ecosystems, promoting research in this 5
field has become inevitable. Here we examined mechanisms influencing and regulating the seedling dynamics of a common Mediterranean dwarf shrub as yet our knowledge about mechanisms causing shifts in community composition and shrub encroachment are very limited. In particular, we analysed the effect of water availability and grazing on the seedling density, establishment and survival. We predicted that increasing water availability will have a direct positive effect on seedlings, while grazing indirectly regulates the negative effect of the neighbouring community particularly with increasing water availability. To test our predictions we conducted a field experiment along a natural rainfall gradient with additional long-­‐term climate manipulations which provides a unique opportunity to investigate the relative importance and potential shifts of biotic and abiotic factors. In contrast to our predictions, shrub seedling density along the rainfall gradient showed a unimodal pattern. Seedling density in the shrub understory increased towards the drier end, due to reduced water -­‐ and light stress. Overall, grazing reduced seedling recruitment, but simultaneously reduced the negative neighbour effect especially with increasing abiotic favourability. Seedling survival showed a reverse trend, i.e. survival increased towards the extreme ends with higher survival in the shrub understory. Our results indicate that climate change, grazing and their combined appearance have a complex but predictable way of affecting seedling establishment. Heike Markus-­‐Michalczyk Willows respond to increasing seawater intrusion – vegetative reproduction capacities in estuaries Coauthor: Kai Jensen Willows had been common components of river floodplain softwood forests in former times. Today, only fragmented willow populations are remaining in densely populated European river mouths like the Elbe Estuary. These tidal willow stands are affected by increasing seawater intrusion due to river deepening and sea level rise. Salix alba and Salix viminalis are typical willow species in European tidal wetlands. Both species are considered as being not salt tolerant. Thus, we investigated the distribution and soil water salinity of both species along the salinity gradient of the Elbe Estuary. We found that both species are able to colonize sites which exhibit oligohaline conditions during the growing season. Based on these findings we conducted an experiment with salinity treatments on cuttings of both species. Cuttings were taken from individuals from both a freshwater and an oligohaline site. Root, leaf and shoot growth, final biomass and chlorophyll fluorescence were measured. In a salinity of 2 chlorophyll fluorescence measurements indicate negative effects on the photosynthetic system. Here, survival of both species originating from the freshwater site and of Salix alba from oligohaline site was reduced to 40-­‐50%. Salix viminalis cuttings originating from the oligohaline site survived with more than 70%. Salix viminalis cuttings from both sites performed significantly better than Salix alba recruits. We conclude Salix viminalis to be more tolerant to seawater intrusion and thus may be useful for flood protection measures in estuaries. Anna Bucharová Effect of land use and climate change on the future fate of populations of an endemic species in central Europe The identification of optimal management strategies for a given species is a major challenge of species conservation. It becomes especially challenging when the environmental conditions are expected to change in the future, and the optimal management applied today may differ from the management that is optimal under the changed conditions (e.g. due to climate change). This study evaluates prospect of a rare plant species endemic to semi-­‐natural grasslands in central Europe, Gentianella praecox subsp. bohemica. The number of populations of this species has declined rapidly in the last 60 years; currently, a conservation action plan has been established in the Czech Republic, where most populations of this species occur. This study uses periodic matrix models to compare different management regimes under different scenarios of climate change and to identify the optimal management in each case. Without management, populations of the species are not able to survive. Flowering individuals can occur for a long time after the cessation of management, but the extinction of the population is inevitable within several decades. Without management, even very large populations (1000 flowering individuals) will go extinct in less than 50 years. Total extinction (including seed bank) will follow several years after observation of the last flowering plant. The most suitable management is mowing and disturbance (by harrowing), which is also the best method for restoration of threatened populations. Mowing is less suitable, but it is fully sufficient for large prospering populations. When management is applied, future climate change may have a relatively small impact on the probability of survival of the species. 6
Session Three -­‐ Friends and Enemies Keynote: Gerlinde B. De Deyn Friends and enemies: better to have old enemies than new neighbours? Plants form the basis for the terrestrial food web and are thereby eaten, dead or alive, by a multitude of organisms. These plant consumers often act as enemies of plant individuals on the short-­‐term, however they can turn out to be friends on longer time scales and/or at plant community level. Moreover plant-­‐feeders may not just act as plant enemies but can have several functions in an ecosystem, depending on their mode of action, their life stage and the abiotic conditions. Notable examples are herbivores that stimulate plant growth, herbivores that serve as pollinators and root mutualistic fungi that act as true mutualists or as parasites depending on plant and soil conditions. Interactions between plants also appear to vary from friendship to warfare. Plant species can facilitate each other through alleviation of abiotic or biotic stress, but plants can also act as ruthless competitors, even engaging in chemical warfare thereby killing competing plants directly or more subtly by poisoning their friends. “Friends” and “enemies” are useful concepts in ecology but organisms are rarely one or the other, and their actual role is depending on the ecosystem context. Overall evidence to date suggests that old enemies are essential to the maintenance of ecosystem functioning, while new neighbours (i.e. invasive species) bear the risk of fast transformation of ecosystems by taking the benefits but escaping the costs in their new environment. Anne Kempel Variation in herbivore resistance among plant species affects plant community structure Plant resistance to herbivores is assumed to be costly as it constrains investment to plant growth and reproduction. However, costs are difficult to detect, mainly because measuring growth and resistance involve difficulties – growth is confounded with the competitive ability of species, whereas resistance depends on the preference and performance of herbivores. Herbivore exclusion experiments are the most natural way to investigate costs of resistance in a community, because if resistance really constrains growth then plant species profiting most from herbivore-­‐exclusion (i.e. suffering most from herbivores) should be the least defended ones. We used data of a long-­‐term herbivore exclusion experiment which assessed the effect of aboveground pesticide application on the cover of plant species. In greenhouse experiments, on 29 of those species we then assessed plant resistance measured as the performance of a caterpillar, and as the preference of the caterpillar and a slug species. Caterpillar performance did not correlate with the response of plants to herbivore exclusion. However, the stronger a plant species profited from herbivore exclusion the more it was indeed preferred by both caterpillars and slugs. Moreover, caterpillar and slug preference were highly positively correlated. Thus, our results provide evidence for costs of herbivore resistance in plants. Further, generalist insect and mollusk herbivores seem to perceive plant resistance in a similar way. We suggest that variation in herbivore resistance, reflected by herbivore preference among plant species, may trade-­‐off with their competitive ability and thereby affect plant community structure. Corina Del Fabbro Allelopathic Effects of three Plant Invaders on Germination of Native Species – A Field Study Co-­‐authors: Daniel Prati & Sabine Güsewell Some plants become highly successful when introduced to new ranges and can even cause major environmental problems. Among several hypotheses explaining the success of these invasive species, the Novel Weapons Hypothesis (NWH) states that invasive species release biochemical compounds to which native species are not adapted and which are therefore harmful to natives (allelopathy). Evidence for this mainly relies on bioassay and greenhouse studies, but field studies are largely lacking. In a field experiment, we investigated whether three invasive species (Solidago gigantea, Impatiens glandulifera, Erigeron annuus) had stronger allelopathic effects on the germination of native species than the adjacent native community. At three sites for each invasive species, we selected invaded and un-­‐invaded plots and neutralized possible allelopathic effects by adding activated carbon to half of them. We then tested the germination of 100 seeds of native species added to each plot. Generally, activated carbon enhanced germination. However, germination was not lower on invaded soils and there was no interaction between activated carbon and invaded vs. un-­‐invaded soils, suggesting that invasive and native species did not differ in strength of their allelopathic effects. Our results do not support the NWH with respect to germination of natives under field conditions. 7
Anna Kladivova How is seedling recruitment and survival in dry grasslands affected by grazing? Coauthor: Zuzana Münzbergová It is generally expected that grazing has positive effects on seedling recruitment by creating gaps in open sward and thus increasing number of suitable microsites for germination. This expectation was supported by several experimental studies. These studies, however, usually only look at the seedling recruitment phase and do not consider if the species are really able to establish at these places. In addition, the existing studies usually do not consider spatial variation in the effects of grazing. The aim of this study was thus to test the effects of grazing on seedling recruitment as well as establishment and to determine the effect of habitat conditions on the results. Blocks of grazed and control plots were established at a dry grassland locality PLA Czech Karst after reintroduction of grazing in 2005. Seedlings of dicotyledonous plants were counted and recorded three times a year. Ellenberg indicator values were calculated for each plot based on species composition. Grazing had a positive effect on seedling germination – both on numbers of seedling and their species composition supporting the rare dry grassland species. Final number of established seedlings was, however, unaffected by grazing. This indicates that seedlings at grazed plots have both higher recruitment but also higher mortality and thus have faster turnover than seedlings in control plots. This clearly indicates that the conclusions of previous studies predicting higher generative reproduction on pastures based on higher number of seedlings observed may be misleading if the species are limited not by recruitment but by establishment as at our locality. In addition, the effects of grazing interacted with the effects of Ellenberg indicator values. Grazing facilitated seedling recruitment in plots with lower light and temperature, and seedling establishment in plots with lower temperature, continentality and pH. Both control and grazed plots showed decreasing recruitment and decreasing mortality of seedlings with increasing nutrient availability. However this effect was stronger for seedlings on grazed plots. The results of the study thus indicate that conclusions based on seedling recruitment can strongly differ on conclusions based on seedling establishment. In addition, they indicate that the effects of grazing strongly depend on habitat conditions at the specific spot, even when working within a single locality. Wayne Dawson More friends at home than away? Comparing mycorrhization of alien and native plant species grown in conspecific and heterospecific soils Alien plant species may benefit from soil enemy release, to the extent that performance on their own soils is greater than that for native species, leading to less negative plant-­‐soil feedbacks and invasion. However, while plant species are believed to be generalist in terms of mycorrhizal symbionts, it is not clear if mycorrhization rates are greater in conspecific or heterospecific soils, and whether mycorrhization rates differ for alien versus native plant species. For 8 alien and 8 native plant species in Europe, we tested if a) mycorrhization differs in conspecific versus heterospecific soils, and b) whether differences in mycorrhization between conspecific and heterospecific soils are less pronounced for alien than for native species. While mycorrhization rates tended to be greater in conspecific than heterospecific soil, there were no clear differences between alien and native plant species in mycorrhization rates, indicating that aliens do not have any mutualist advantage (or disadvantage) compared to native species, whether they are growing on conspecific or heterospecific soils. Jana Raabova Mycorrhizal symbiosis as the key factor for local adaptation in a perennial herb Local adaptation is common in plants, but also in arbuscular mycorrhizal fungi. Mycorrhizal fungi are mostly beneficial for plant growth. Therefore, they may be important for local adaptations of plants. Previous studies demonstrated beneficial effects of mycorrhizal symbiosis in our model perennial herb Aster amellus as well as strong adaptations of this plant to local conditions. Here, we devote special attention to the interrelation between the locality, soil composition and mycorrhizal symbiosis. We expect that the combination of all these three factors is important for local adaptation of plants. We recorded plant fitness in a reciprocal field transplant experiment. Furthermore, we determined mycorrhizal root colonization and aboveground biomass for each plant when harvesting the experiment after 5 years. The percentage of root colonization significantly depended on nutrient content of both the target site and the population of origin of the plant. In nutrient-­‐poor soil, the lack of nutrients is compensated by the activity of the fungus, resulting in high root colonization. In contrast, the root colonisation is low in nutrient-­‐rich soil. After reciprocal transplant, plants from the nutrient-­‐poor soil had high root colonization also in the nutrient-­‐rich soil and plant growth was comparable with the native plants. In contrast, plants from the nutrient-­‐rich region did not sufficiently increase their root colonization in 8
nutrient-­‐poor soil and their growth was thus reduced compared to the native plants. To conclude, including mycorrhizal symbiosis into studies on local adaptations may increase our understanding of mechanisms by which plants are adapting to their environment. Katrin Heer Population genetic analysis of hybridization of fig species in Central Panama The obligatory mutualism of figs (Ficus sp., Moraceae) and their pollinating fig wasps (Agaonidae) is one of the most specialized plant-­‐animal interactions known. For a long time, the mutualism was believed to be strictly species-­‐specific. Consequently, tight cospeciation and thus, congruence of the phylogenetic tress of wasps and figs was expected. However, recent studies have caste doubt on the strict one-­‐to-­‐one relationship. Genetic studies have found discrepancies of the phylogenetic trees of figs and wasps at the species level, providing evidence of host switches of fig wasps and the possibility of hybridization among fig species. The discovery of fig wasp species pollinating more than one fig species and have reinforced this hypothesis. In our study we focused on 11 Ficus species belonging to two distantly related subgenera, Urostigma and Pharmacosycea occurring in Panama. Under the assumption of gene flow among closely related species we would expect to find hybrids as well as introgressed individuals, and genetic demes that span species boundaries. Using 10 polymorphic microsatellite DNA loci, we applied a Bayesian cluster analysis to test whether morphological species concur with the assignment to genetic clusters based on genotype frequencies. The Bayesian analysis assigned all investigated species to separate clusters. However, we found a few putative hybrids and introgressed individuals among the studied species. In our study, neotropical fig species were genetically distinct although there was limited evidence for interspecific gene flow. Session Four -­‐ Novel Genotypes and Extreme Events Keynote: Ray Callaway Novelty and community organization Phylogenetic and trait-­‐based novelty has the potential to affect the successful entry of species into communities and the impact of these species on others after they enter. Novel ‘niche space’ may allow species to coexist through minimizing competitive interactions, whereas novel ‘traits’ may either lead to disproportionate disadvantages or advantages in competitive, consumer, or mutualistic interactions. Exotic invasions have the potential to reveal some aspects of advantages and disadvantages inherent to niche and trait based novelty, and in particular through biogeographic comparisons of interactions in the native and non-­‐native ranges of exotic invaders. Jake Alexander Climate adaptation across the native and introduced ranges of an invasive plant Understanding evolutionary responses of non-­‐native plants to environmental variation as they spread in a new range, and the limits to these responses, is important for predicting plant invasiveness. This requires knowledge of the introduction history of a species, as well as extensive population sampling across the whole native and introduced ranges. Molecular markers (7 SSR loci) strongly suggest that the invasive plant Lactuca serriola has been introduced from Europe into other regions of the world (North America, South Africa and Australia) with widely different climates. This expansion has been accompanied by the evolution of flowering phenology to match the local climate, which for some introduced populations is outside of the variation in both phenology and climate observed in putative source populations. Furthermore, introduced plants flower faster than native plants even after accounting for climate. However, the variation in phenology observed among introduced populations does not exceed that found in warmer and drier parts of the native range in Asia, which did not contribute genes to the invasion. This suggests that while the evolutionary potential of introduced populations is great, they are not able to transgress the limits of phenological variation found in the native range as a whole. If so, this has important implications for understanding the ability of native populations to adapt to rapid climate change. 9
Petr Dostal Impact of giant hogweed on native communities changes along invasion chronosequence From the impact assessment of exotic species on native communities we know that exotic invaders may reduce species richness of invaded communities. The impact is, however, usually assessed in a single time point despite it can change over time. In this study we analyzed the effect of invasive exotic species Heracleum mantegazzianum (giant hogweed) on characteristics of native communities (richness, composition and biomass production) at sites differing in invasion history. We did our surveys at uninvaded sites and at sites that were invaded ca. 11, 28, 42 and 48 years ago, each site type represented by five replicates. We also measured differences in hogweed cover and soil abiotic properties there. We showed that richness and biomass production changed unimodally along invasion chronosequence: native diversity and biomass were greatest at uninvaded sites and declined up to age of hogweed populations of 28 years. In older populations, however, recovery in diversity and biomass was observed. Similar unimodal pattern was observed in native species composition. The soil properties (pH, phosphorus content, conductivity) increased linearly with the age of hogweed stands. Changes in invaded native communities can be explained by decreasing hogweed dominance in time. It is likely that hogweed accumulates pathogens as it was shown in a complementary common garden study. Hogweed mortality increased and competitive ability decreased, respectively, in unsterilized soil sampled in older hogweed stands. This study provides evidence that temporal context cannot be ignored when studying the impact of invasive species on native communities. Christian Sailer Apomicts Compete Better Than Sexuals Apomixis, the clonal propagation through seed, is known in more than 40 plant families (Asker & Jerling). This widespread phenomenon can fix a successful genotype, resulting in a fitness advantage. On the other hand, this fitness advantage is expected to be lost if the environment changes. Nonetheless, some species are apomictic and successful since decades. Here, successful apomictic Hieracium pilosella L. from New Zealand and sexual plants from Europe have been compared for their vegetative competitiveness. Therefore, plants of the sexual type and plants of the apomictic type were grown with the same type (no competition), in competition with the other type (intra-­‐species competition) and/or in competition with the grass Bromus erectus (inter-­‐
species competition). The experiment was performed in a common garden in Zürich in summer 2009. Three variables were tested using mixed-­‐effects models: Biomass, stolon-­‐count and longest-­‐stolon. For biomass, stolon-­‐
count and longest-­‐stolon, apomicts performed generally better. However, for stolon-­‐count and longest-­‐stolon sexual plants exhibited a better inter-­‐species competitiveness. For all other competition levels, no effects were found. Sexual plants show an overall better inter-­‐species competitiveness than apomictic plants in terms of vegetative growth, while apomicts are generally bigger. However, further experiments are needed to disentangle the effects of the genetic background and the mode of reproduction. Alistair Jump Extreme events tip the competitive balance within and between tree species Many of our predictions of how communities will react to changes in climate are derived from an understanding of how growth and reproduction respond to changing mean conditions. However, extreme events are expected to be more important than average conditions in many respects – leading to sudden switches in state rather than gradual changes. Based on data from a long term monitoring site in mixed temperate forest in the UK, I will report how an extreme drought event altered the competitive interactions between co-­‐occurring individuals of Fagus sylvatica and between this species and Quercus petraea. I will discuss how a combination of rapid response to drought and slow recovery modulates competition in this system and leads to sudden changes in dominance between these species. 10
Michal Gruntman Increased plasticity in ecophysiological traits of invasive Impatiens glandulifera genotypes Phenotypic plasticity, which confers a fitness advantage under heterogeneous and novel conditions, has been commonly suggested to be selected for in invasive plants following their introduction. Several studies have examined the evolution of plasticity in invasive plants, but these were mainly restricted to morphological traits. Here, we compared plasticity in both morphological and physiological traits associated with shade tolerance between native and introduced genotypes of the invasive plant Impatiens glandulifera that were grown in a common garden under two light regimes. Invasive plants exhibited greater plasticity in leaf-­‐level traits, including specific leaf area and photochemical responses. These responses provided invasive I. glandulifera with greater utilization of high light levels compared to native plants, e.g. via increased maximal photosynthetic rate, and enabled greater fitness homeostasis over the two light regimes. These results support the hypothesis that phenotypic plasticity may be selected for in invasive-­‐range populations and suggest that shade-­‐induced plasticity could have facilitated the spread of invasive I. glandulifera in disturbed, un-­‐shaded habitats. Michaela Zeiter Invasibility of Swiss grasslands: interactive effects of summer drought, site productivity and propagule pressure Ecological processes resulting from global change, such as more frequent extreme summer drought or increased propagule pressure of exotic species, often affect plant communities gradually and may therefore not often be distinctly recognised. Studies have clearly shown that adding more or less seeds of an invader species to sites affects their establishment success. The relative importance of propagule pressure compared with other factors influencing establishment success, such as disturbance and resource supply, is not known. We performed a seed-­‐addition experiment in twelve semi-­‐natural hay meadows, one of low productivity (~300 g/m2) and one of high productivity (~700 g/m2) in each of six regions of Switzerland. At each site, we manipulated summer precipitation (‘summer-­‐drought’ and ‘normal’ scenario, n = 3) using rainout-­‐shelters (5 × 5 m) from mid June to end of August 2010. Propagules of 36 species of different origin (‘indigenous’ vs. ‘non-­‐indigenous’) were added as inocula of different density (40000 seeds/m2, 5000 seeds/m2, control) to small areas (18 × 36 cm) nested within the climate treatment. We expect that a potentially positive effect of summer drought on invasibility will be especially high at sites of high productivity, where, under normal weather conditions, invasion success is reduced due to high competition for light. Moreover, we expect that propagule pressure has lower impact at high productivity. We present preliminary results based on establishment success of the invaders measured one year after seed addition. Harald Auge Interactive effects of biological invasions and herbivory on diversity and productivity of grassland ecosystems Previous biodiversity experiments showed that plant diversity positively affects ecosystem functions such as primary production. Since these experiments were done using artificial plant communities, the relevance of these findings for real ecosystems remains to be confirmed. Furthermore, they usually marginalized the role of other trophic levels and considered the loss of native biodiversity but ignored the invasion by exotics. Since species interactions are shaped by a co-­‐evolutionary history among species, it can be hypothesized that emerging ecosystem properties differ between communities composed of native species and communities invaded by exotics. In spite of the importance of biological invasions, experimental studies testing this hypothesis using real ecosystems are lacking. We therefore initiated a seed addition x herbivore exclusion experiment on 10 grassland sites, covering a wide range of diversity and productivity, in Central Germany. At each site, we established rodent exclosure and control plots, and added either a seed mixture of 20 native species, of 20 exotic species, or no additional seeds. The same experiments were set up in California and Montana, which will enable us to separate general patterns from regional peculiarities in ecosystem response. Here, we report on results from German and Californian sites. In contrast to our expectation, establishment of added native and exotic species was positively related to diversity of resident species. Recruitment of additional species resulted in an increase in productivity, which was much higher in case of exotics. Herbivore exclusion magnified this effect, suggesting biotic resistance of grasslands against invasions mediated by herbivory. 11
Session Five -­‐ Causes and Consequences of Diversity Keynote: Helene Muller-­‐Landau Quantifying contributions to diversity maintenance: using population biology to address community-­‐level questions Coauthors: Marco Visser, Matteo Detto, Eelke Jongejans, Ryan Chisholm, Hans de Kroon, Frederick R. Adler, and S. Joseph Wright Understanding and quantifying the contributions of different mechanisms to diversity maintenance in local communities is a key challenge for basic ecology, and one with important applications in biodiversity conservation. Recent work proposes that contributions be assessed in terms of effects on individual species invasion growth rates. The argument has further been made that only evidence of mutual invasibility is effectively evidence of species coexistence rather than co-­‐occurrence. We argue that stabilization, rather than invasion growth rate, is a better focus for research on contributions to diversity maintenance. By stabilization, we mean the negative density-­‐dependence of long-­‐term per capita population growth rates. This is distinct from (though related to) local negative density-­‐dependent effects of conspecifics. We present a case study investigating how the spatial scales of interactions with natural enemies influence the strength of stabilization as well as the local signature of Janzen-­‐Connell effects in model plant communities. We show that stabilization is strongest when enemy dispersal distances are longest – and local Janzen-­‐Connell effects are least apparent. Finally, we discuss the challenges of quantifying stabilization in high-­‐diversity communities of long-­‐lived organisms in which multiple mechanisms are operating, and provide strategies for overcoming these challenges. Anne Petzold Does neighbourhood implies fatherhood? – A contrary from paternity analysis in P. euphratica Coauthors: Ronald Bialozyt & Martin Schnittler Paternity analysis based on genotyping trees via seven polymorphic microsatellite loci was used to investigate pollen dispersal and gene flow within a large open woodland of riparian, wind-­‐pollinated Populus euphratica in China. The study population consists of 282 male (potential fathers) and 236 female trees. Fruits from 6 mothers were collected and seeds germinated in the greenhouse. From these a total of 445 seedlings have been selected for genotyping and paternity analyses with CERVUS software. Preliminary results of paternity analyses showed, that most of the detected fathers grow in a distance of 200-­‐1000 m to the mother tree, although the next putative father grows usually in less than 50 m distance from a mother tree. Since the efficiency and therefore the reproductive success are generally assumed to decrease with an increasing pollination distance, we investigated flowering-­‐time differences among the sexes to find an explanation for this discrepancy. Therefore, we mapped flowering start and duration for 122 male and 115 female trees in the study area. To simulate pollen flow as a function of flowering-­‐time differences we programmed a spatially explicit, individual-­‐based simulation model which is able to use different functions for pollen dispersal. Running the model for a large number of simulations with flowering times for each tree determined a) according to the really found pattern, and b) at random with different degrees of overlap between trees, we want to estimate the influence of synchronisation of individual flowering time on paternal distances and genotypic diversity of the offspring. Yuan-­‐Ye Zhang Putting epigenetic variation into perspective: a comparison of phenotypic variation among epiRILs, RILs and natural populations of Arabidopsis thaliana To explore the potential evolutionary consequences of epigenetic variation, researchers have created epigenetic recombinant inbred lines (epiRILs; highly variable at the level of DNA methylation but nearly identical in DNA sequence) of Arabidopsis thaliana. Quantitative genetic studies with these lines have found significant heritabilities of complex traits. Although this suggests a possible role of epigenetic variation in microevolution, it remains difficult to assess its true significance because of a lack of rigorous comparisons of epiRIL variation with the variation found in other systems used to explore variation in quantitative traits. In a common garden experiment, we compared phenotypic variation in subsets of two epiRIL and two genetic RIL populations, as well as within two natural populations and among geographic collections of Arabidopsis ecotypes. We find significant trait heritabilities in all of these groups, including epiRILs, but there is a tendency for epiRILs to be slightly less variable than genetic RILs and natural populations, while variation is greatest among geographic ecotypes. Nevertheless, for one of the epiRIL populations, magnitudes of phenotypic 12
variation are comparable to those found among genetic RILs and within natural populations, which shows that epigenetically-­‐based variation is significant and of comparable order of magnitude as true natural variation. Bastian Steudel Biodiversity effects under stressful environmental conditions Increases of ecosystem functioning with increasing biodiversity are well documented for stable or non-­‐stressed systems. However, although natural ecosystems are frequently faced with environmental fluctuations, how biodiversity-­‐
functionality relationships are affected by environmental stress or changes is less studied and the underlying mechanisms have barely been explored. We report on experimental studies using marsh plant communities subjected to three different stress types (drought, salt, shade) that show that increases in biomass are independent of the stress type, and that the increases were due to complementarity effects (i.e., increases of ecosystem function for most species). In an experiment using micro-­‐algae, we further show that stress intensity influences the strength of the biodiversity effect along a temperature and a salt gradient. Different measurements of biodiversity (i.e., species richness, genetic diversity based on SNP number, and phylogenetic diversity) showed similar patterns of diversity dependent increases of biomass in this experiment. In combination, our experimental findings show that biodiversity, independently of the measurement, leads to an increase of biomass under stressful environmental conditions. This increase calls for the conservation of biodiversity, not only species richness, but also of genetic diversity. Dan Flynn Limited phylogenetic niche conservatism for plant functional traits A major challenge in the use of phlylogenetic information in community ecology is the assumption substantial phylogenetic niche conservatism exists in functional traits relevant for community interactions. To address this challenge, we use uniquely detailed plant functional trait and molecular phylogeny datasets for 60 grassland species in Jena, Germany, with multiple trait measurements made both within species and over time. We test 1) whether plant functional traits demonstrate significant phylogenetic niche conservatism; 2) whether traits for resource acquisition, competitive ability, or life history differ in the amount of phylogenetic niche conservatism; 3) whether such conservatism extends to both mean trait values and the intraspecific variability in traits; and 4) how such conservatism or lack thereof would alter conclusions drawn from studies of phylogenetic patterns for community assembly or biodiversity–ecosystem functioning relationships. The strength of phylogenetic signal assessed for 52 plant trait means varied widely. Trait mean values related to plant size and nutrient acquisition and use consistently exhibited significant, but not large, phylogenetic signal. Means of flowering phenology, specific leaf area, and allometric ratios exhibited no significant phylogenetic signal. The degree of intraspecific variability was not conserved for any trait except individual height. These results show that the use of phylogenetic relatedness in community ecology cannot easily be directly linked to commonly-­‐measured morphological and physiological traits. Both mean values for species and the variability of such values within populations for traits that drive community interactions may be the product of forces other than phylogenetic history, for example shorter-­‐term evolutionary adaptations or plastic responses within species. Christian Lampei Nitrogen content of the Arabidopsis thaliana transcriptome is determined by population size and evolutionary factors other than selection for nitrogen efficiency Recently, it was suggested that selection for nitrogen efficiency may be acting on the major biopolymers of species to reduce nitrogen content. These conclusions were based on comparisons between evolutionary distant taxa. Studies on a smaller time scale, e.g. within species, should provide additional insights into the factors acting on elemental composition, which can be of ecological or purely evolutionary nature. In this study we utilize genome resequencing data from 80 A. thaliana accessions to analyze the composition of their transcriptome. If the A. thaliana transcriptome is under selection for nitrogen efficiency we expect to find single nucleotide polymorphisms (SNPs) that increase the N-­‐
content at a reduced rate and this negative correlation should be stronger in neutral SNPs than amino acid changing SNPs (nsSNPs). Finally, we expect a negative correlation of N-­‐difference caused by a mutation with the effective populations size (Ne), because natural selection is more efficient in larger populations. In contrast to our expectations, a positive correlation was found between N-­‐difference and the allele frequency and it was strongest in nsSNPs. Also, an ANCOVA showed a significant interaction between Ne (8 populations) and a factor of SNP-­‐classes, suggesting that private nsSNPs decrease the transcriptome N-­‐content in small populations. These results show that the transcriptome of A. thaliana is currently not under selection to increase nitrogen efficiency. Instead we see side effects of interacting 13
evolutionary factors like mutational bias, purifying selection and molecular repair mechanisms such as GC-­‐biased gene conversion. Our results suggest that N-­‐content differences among species transcriptomes should be interpreted with care. Vit Latzel Epigenetic diversity increases ecosystem functioning During the past two decades, a large body of ecological research demonstrated that both species and genetic diversity promote ecosystem functioning, i.e. they have positive effects on important ecosystem processes such as productivity, stability or nutrient cycling and thus, ultimately, on ecosystem services and human well-­‐being. Here, we extend, for the first time, the concept of functional biodiversity to the epigenetic level, and we experimentally tested the functional consequences of changes in epigenetic diversity. We used epigenetic recombinant inbred lines (epiRILs) of Arabidopsis thaliana to create replicated populations of contrasting epigenetic diversity (1, 2, 4, 16 epigenotypes) and subjected these populations to a factorial combination of pathogen attack or competition by other annual weeds. We find that, overall, epigenetic diversity significantly increased the productivity and pathogen resistance of populations, as well as their resistance to invasion by other weeds. In the presence of pathogens or competitors, epigenetically diverse populations achieved a 20-­‐40% higher biomass than epigenetically uniform populations, and they were also more successful in suppressing the growth and reproduction of other weeds. Our study is the first experimental demonstration that epigenetic diversity, just as species and genetic diversity, alters the productivity and stability of populations and ecosystems. Epigenetic diversity thus could be an important, but so far overlooked, level of natural biodiversity. Sabine Both Biodiversity and ecosystem function across structural strata in a subtropical forest in China Tree layer characteristics such as tree species diversity, species composition and forest stand age have the potential to affect herb layer vegetation. Knowledge of interactions between understory herb and overstory tree layer is mostly restricted to temperate, comparatively species poor forests. In the framework of the BEF-­‐China project an observational approach was conducted in diverse near-­‐natural subtropical forest stands that differ with regard to their successional age. The main objective was to investigate whether a species-­‐rich overstory promotes a species-­‐rich understory, i.e. whether diversity is positively correlated across structural strata. In addition, the relationship between diversity and productivity across structural strata was analysed. This research is based on the assumption that ‘bottom-­‐up’ effects from the herb to the tree layer prevail in early successional communities, while ‘top-­‐down’ effects become the dominant mechanism in mature forest stands. A species survey revealed that herb layer species richness was high, ranging between 25 to 71 vascular plant species per 100 m2, but was uncorrelated to tree layer diversity. Herb layer composition followed a successional gradient, demonstrated by non-­‐metric multidimensional scaling (NMDS), however, diversity was not correlated to successional forest age. Herb layer productivity was neither affected by tree layer nor by herb layer diversity. In contrast to other forest ecosystems, woody species, presented by tree seedlings and saplings, contributed extraordinarily to overall herb layer diversity in all successional stages while herbaceous species were less prominent. Contrary to expectations, diversity-­‐diversity and diversity-­‐ecosystem function relationships were not coupled across structural strata. 14
Posters Please hang your posters the morning of May 17th before the Session One begins. Pushpins will be available for use. 1. Bettina Springer Fluctuating asymmetry in plants along steep and subtle environmental gradients – the role of biotic interactions (Cyperaceae)Fluctuating asymmetry (FA), the random, non-­‐directional deviations form perfect bilaterally symmetrical morphological structures, is the most commonly used estimate of developmental instability (DI). DI reflects the ability of an organism to buffer its development against environmental disturbances. Therefore an increasing interest in FA over the last decade emerged, because FA has been proposed as an indicator of environmental stress. Previous studies have shown that FA variance of populations and absolute FA values of individuals increases with cumulative stress. In this study the aim is to ascertain FA responses to environmental stress along different gradients such as aridity, productivity and temperature to ensure whether or not FA is an indicator of habitat quality. Based on the assumption that environmental stress reduces the availability of an organism to maintain developmental precision we expect the level of FA to be greater in stressful environments than in environments which are more benign. According to the stress gradient hypothesis we also predict that in stressful environments the level of FA is less in plants growing in the immediate vicinity to shrubs compared to the level of FA of plants which are growing in open areas 2. H.M.Mahadeva Swamy Cloning and expression of a novel CRY1I gene from Bacillus thuringiensis isolates and its toxicity against Myllocerus undecimpustulatus undatus Marshall (Coleoptera: Curculionidae) and Helicoverpa armigera Hüber (Noctuidae: Lepidoptera) The six isolates of Bacillus thuringiensis from Andaman and Nicobar Islands which were previously characterized by PCR analysis for the presence of Coleopteran active cry genes were used for Cry1I full length gene amplification. A 2.16-­‐kb DNA fragment of Cry1I gene was PCR amplified, cloned in expression vector pQE 80 L, and then used for transformation of E. coli M15 cells. The optimum expression was obtained with 1 mM IPTG at 370C for 3 h. The sequence of the cloned crystal protein gene showed almost complete homology with a Cry1I toxin gene from Bacillus thuringiensis var. kurstaki, with scattered mutations in the toxic region. The deduced sequence of the protein has homologies of 91.0% with Cry1I and Cry1Ia, and 98.0% with Cry1Ib. Cloning of this gene may help to overcome the increasing resistance of pests to currently used insecticides. Based on the results obtained, the PCR method may be a valuable and reliable tool for specific detection and identification of cry1I genes. The toxicity of Bt recombinant protein was determined against first instar larvae of Myllocerus undecimpustulatus undatus Marshall (Coleoptera: Curculionidae) and Adults; Helicoverpa armigera Hübner (Noctuidae: Lepidoptera) at 310µg/mL and 15.5µg/mL respectively. The novel cry1I gene will be an important resource in constructing genetically engineered bacteria and transgenic plants for biocontrol of insect pests and Bt based biopesticidal formulations, aiming to reduce the use of chemical insecticides. 3. Jasmin Joshi Impact of soil negative feedbacks on plant species diversity Recent research indicates that plant-­‐soil feedbacks may contribute to explaining a large proportion of the relative abundance of plant species in communities and therefore to mechanisms enabling species coexistence. We used the framework of the Biodiversity Exploratories to test whether plant species with large individual biomass production that are not locally dominant are most strongly limited by specific negative soil feedbacks. In addition, we tested the effect of land-­‐use intensity on biotic plant-­‐soil feedbacks. First experimental results will be presented 4. Christine Heiniger Performance differences between rare and common species growing in botanic gardens Research on rare species has been dominated by studies of single threatened species. Limitations of this approach are that it involves no comparison with common species and that single-­‐species approaches prevent generalization about consequences of rarity. In 2010 and 2011 we used 166 plant species grown in all or most of 10 botanic gardens in Switzerland to examine the relationship between rarity or commonness with species performance traits, including survival, reproductive success, growth and susceptibility to herbivory. Rarity and commonness were assessed according 15
to range size in Switzerland and alternatively also according to red list status. Rarity or commonness was not related to species survival and growth. However, more common plant species showed higher reproductive success, and also higher susceptibility to herbivory than less common ones. The former suggests that reproductive differences contribute to commonness, and the latter that reduced herbivory damage of rarer species does not outweigh the reproductive advantage. Our study supports the notion that some of the variation in commonness and rarity among species is due to species characteristics, and highlights that botanic gardens with their diverse species collections are interesting study platforms for multi-­‐species comparison. 5. Tomáš Dostálek Changes in biotic interactions between primary and secondary range as an explanation for species invasions The objective of our study is to determine whether there are shifts in biotic interactions between the native and new range of plants that are expanding their range due to global warming. Furthermore, we aim to investigate whether these shifts have led to plant population differentiation between the native and the new range. Plants may be released from natural enemies in their new range, which can lead to the invasion of these range expanding plants. Plants in the new range can potentially invest less in defenses and more into growth. The study plant is Rorippa austriaca, native to the Czech Republic but recently expanding its range to NW Europe where it has become invasive. In common gardens in the new range (Netherlands, Germany) and native range (Czech Republic), the performance of different native (Czech) and exotic (Dutch, German) populations with and without herbivores will be investigated. This will reveal whether insect communities in the native and new range differ in their effect on the plants and whether populations are adapted to these different biotic interactions. Moreover we will perform soil feedback experiments to test whether plants experience more negative soil feedback in the native range than they do in the new range. Experimental design will be presented. 6. Andy Tedder Emergent androdioecy in the typically hermaphroditic Arabidopsis relative, Cardamine amara. While the predominant reproductive strategy in angiosperm taxa is hermaproditism, deviation from this system, particularly in the form of dioecy is relatively common. Examples of the intermediate precursors to both of these extreme systems are also found, however androdioecious (male only individuals maintained in a hermaphroditic system) systems are incredibly rare, likely due to the inherent reproductive disadvantage losing female function infers. Here we demonstrate that Swiss populations of the predominantly outcrossing Cardamine amara (Brassicaceae) are maintaining both hermaphroditic individuals and female-­‐sterile ‘males’ (a simple recessive trait) in proportions varying from 0% ‘males’ to 55% ‘males’. Moreover, despite the theoretical requirement for the fitness of imperfect ‘males’ (measured here by pollen number, fertility, and offspring germination rate) to be a minimum of two-­‐fold higher than that of male fitness in hermaphrodites, we find that imperfect ‘males’ do not show increased fitness (in fact lower pollen number per flower), but instead only maintain an approximately equal fitness by increased asexual reproduction (via stoloniferous growth). We postulate several theories that may go some way towards explaining how an androdioecious system could evolve and be maintained under these conditions. 7. Rolf Holderegger Population re-­‐sequencing reveals the signature of habitat-­‐mediated selection in Arabidopsis halleri Understanding the nature of genetic variation is of long-­‐standing and general interest in evolutionary biology. In the face of heterogeneous environmental conditions, natural variation is essential for the adaptation of plants to their environment and changing climatic conditions. We examined plant adaptation on a genome-­‐wide scale in the non-­‐model organism Arabidopsis halleri, a strictly outcrossing species. Three populations of A. halleri were investigated from an ecological and population genomic perspective by using a next-­‐generation genome re-­‐sequencing approach of pooled population samples. The three investigated populations follow a West-­‐East transect in the within Switzerland, with pronounced differences in climatic factors, including frost, solar radiation, moisture and precipitation. By mapping more than 390 million paired-­‐end Illumina reads against the reference genome of the closely related model species A. thaliana, we found 2,097,662 SNPs. Outlier SNPs and strongly differentiated genomic regions were identified using FST–based approaches. Our results identified multiple candidate genes, whose functional annotation revealed links to specific environmental conditions. Further, the top outlier SNPs were tested for association to climatic factors with a landscape 16
genetic approach. Several outlier SNPs were found to be associated with climatic factors, suggesting that environmental factors may drive adaptation to local environmental conditions. Furthermore, outlier genes that were identified by mapping against the reference genome of a close relative were validated on de novo assembled contigs of the A. halleri genome. 8. Annette Kolb Genetic variation affects early, but not late life-­‐cycle stages in fragmented populations of a perennial herb Habitat fragmentation is a large threat to biological diversity worldwide, with negative effects on organisms arising as a result of changes in the abiotic or biotic environment and via changes in genetic processes. We examined genetic diversity, population structure and gene flow as well as the importance of genetic diversity for plant and population performance in 17 differently-­‐sized populations of the self-­‐incompatible, perennial forest herb Phyteuma spicatum. Results conformed to those of other studies conducted in fragmented systems; we detected overall low levels of genetic variation, significant population differentiation and restricted gene flow among populations. Interestingly, only seedling vital rates appeared to be influenced by population genetic parameters, while later life-­‐cycle stages and population growth rate were not affected. This suggests that deleterious alleles are purged early in the life cycle, releasing older individuals from their genetic load, and that populations may be able to buffer the negative genetic effects of small population size. The overall low levels of genetic diversity, however, imply that populations are less able to respond to future changes in the environment, which is of special concern as colonization of new sites in response to putative changes in the environment is unlikely. 9. Lucienne de Witte What makes a homeotic orchid mutant successful? How novelties in morphology originate during evolution is still controversial among biologists. Homeotic plant mutants that are able to establish stable populations in the wild, so-­‐called “hopeful monsters”, prove that a saltational mode of character change is a potential alternative mechanism for speciation. Coelogyne fimbriata is a food-­‐deceptive orchid species that is pollinated by female wasps. Since 1990, a natural population in Hong Kong is known, in which the plants bear flowers with a homeotic transformation: the second perianth whorl has changed organ identity, therefore, petals and lip are sepal-­‐like. Our study of the micromorphology, ontogeny and developmental genes revealed that this homeotic mutant represents a hopeful monster that survived in the wild for more then 20 years. We will investigate plant-­‐
pollinator interactions and population fitness of the homeotic mutant Coelogyne fimbriata var. leungiana to make comparisons with the wildtype and to find out how this mutant successfully survives in the wild. 10. Masaki Kobayashi Ecological Transcriptome Analysis of Synchronous Flowering in Tropical Rainforest In the Southeast Asian tropics with little seasonality, a community-­‐level mass flowering called “general flowering” is observed with irregular intervals. We examined large-­‐scale gene expression patterns before the formation of flowers in one of the dominant mass flowering species, using “the ecological transcriptome” approach. We discuss a view of a complex transcriptional network associated with environmental and endogenous factors during the induction of intermittent synchronous flowering. 11. Maja Al Beyroutiová Structuring of populations of recently evolved plant species Coauthors: Švec, M. – Sabo, M. – Dušinský, R. – Michalcová, V. -­‐ Hauptvogel, P. We focused on the estimation of optimal number of subpopulations of the Aegilops cylindrica Host. species (goatgrass) by comparing effectiveness and quality of structuring by five statistical methods. We used a file of binary data obtained from 270 molecular markers representing DNA polymorphism of DArT type. The statistical method self-­‐organizing maps (type of neural network) separated the 60 samples of goatgrass native to Transcaucasia, Turkey, Balkan and the Central Europe into 4 clusters. Multidimensional scaling (MDS) method distributed all the analysed samples into the 2D space in the framework of which we estimated 5 clusters. Using model-­‐based clustering method (STRUCTURE software) and by application of Wilcoxon test, we assigned 5 subpopulations as optimal number of clusters in the whole population. The 17
same optimal number of subpopulations was also estimated by means of hierarchical clustering. According to method of partitioning around medoids (PAM), the optimal number of subpopulations in the whole population of Aegilops cylindrica species is equal to 8. We realized cluster validation by means of connectivity and Dunn indices. Our results indicate that the most suitable methods for the population structuring are the self-­‐organizing maps and hierarchical clustering, followed by multidimensional scaling, model-­‐based clustering and partitioning around medoids. We recommend the neural network for practical use in the population biological studies because of its quality and simplicity. Acknowledgement "This work was supported by the Slovak Research and Development Agency under the contract No. APVV-­‐0661-­‐10, APVV-­‐0197-­‐10". 12. Karin Kaljund and Malle Leht Differential recolonization of disturbed habitats by Medicago sativa ssp. falcata, a rhizomatous herbal legume Dispersal of a plant population through colonizing spare space depends on many factors, primarily on the dispersal ability by seeds or pollen. Crucial for the establishment by seeds are requirements for germination conditions and vegetation cover in the colonized area. Dispersal determines the structure and dynamics of populations and affects genetic structure within and among founded populations. We studied the genetic variability and differentiation in three populations of sickle medic, a clonal outcrossing legume, using four selected polymorphic isozyme loci to compare source populations with nearby newly established sites. Plants in the source populations were evenly distributed and leaf samples were collected along one to two linear transect. In the newly established population parts, an abandoned sandpit and an overgrowing sand dune, plants showed patchy distribution and leaf samples were taken from separate patches. We found that the overall observed heterozygosity Ho was equally high both in the source populations and in the colonized sites ranging from 0.66 to 0.95. One population did not show genetic differentiation between older and nearby younger population parts (Fst=0.004). In contrast, in two other populations Fst ranged between source sites and newly established parts from 0.14 to 0.29, reflecting differences in allele frequencies. These results indicate that recolonization of disturbed nearby sites by seed dispersal to multiple small founder patches and seedling establishment followed by the clonal growth has not reduced Ho by combining high individual heterozygosity of established founder plants. 13. Kevin Kit Siong Ng Genome-­‐wide polymorphism study in a non-­‐model timber tree Shorea leprosula using next-­‐generation sequencing Shorea leprosula is an economically and ecologically important tropical timber in Southeast Asia. It belongs to the Dipterocarpaceae family. It is distributed from Southern Thailand (Pattani), throughout Peninsular Malaysia (except for the seasonal areas in Perlis, northwest Kedah and Langkawi Island), Sumatra and to Borneo. Establishing a set of genetic markers, which can be used to access regions of the genome involved in local adaptation is important to understand fundamental similarities and differences between populations of S. leprosula. Once the markers are established they can be further studied to look for signatures of selection to any number of evolutionary forces. Single nucleotide polymorphisms (SNPs) are a useful starting point to scan large and disparate regions of the genome due to their abundance in both coding and non-­‐coding regions, their co-­‐dominant nature, and lack of ambiguity. In the absence of a reference genome sequence of S. leprosula (genome size: ~450Mb), the strategy of our study is to assemble (de novo) short reads with high genome coverage and subsequently, annotating the contigs/scaffolds. Using similar method, we choose to generate NGS data for 96 individuals of S. leprosula from 16 natural populations throughout the distribution range in Southeast Asia to identify large numbers of SNPs by mapping and aligning onto the annotated contigs/scaffolds. SNPs identified from all individuals will be used to investigate the genome-­‐wide polymorphism for genetic boundaries delineating S. leprosula population structure and/or substructuring by understanding the main genomic processes shaping the variation. 14. Janosch Sedlacek Ecological variation and adaptive potential of alpine shrubs in the Swiss Alps Climate change is expected to significantly impact growth, phenology and fitness traits in alpine plants by altering temperature regimes and snowmelt timing. Our study examines the ecology, phenotypic plasticity and 18
microevolutionary potential of Salix herbacea, a common Arctic-­‐alpine shrub. We examined variation in phenological, ecophysiological, morphological and fitness-­‐related traits, and neutral molecular markers in S. herbacea along elevational and snowmelt gradients in the Swiss Alps to determine a) environmental, biological and genetic drivers of variation, and b) the potential adaptive response of this species to a warming climate. S. herbacea individuals (1680) were monitored across two microhabitat types (early-­‐snowmelt ridges and late snowmelt beds) along three elevational transects. A reciprocal transplant experiment was established, transplanting clonal fragments between microhabitat types to observe phenotypic plasticity. Neighbour removal plots were established to determine the facilitative/competitive interaction balance between Salix and the surrounding community. Phenological status (leaf, flowers, fruits) was recorded weekly and leaf morphology, non-­‐structural carbohydrates, stem growth/density and genetic data were collected. Preliminary results show S. herbacea demonstrate high phenotypic variation in peak flower and fruit counts and duration, leaf area and mass, and stem density; these trait variations were strongly connected to snowmelt time. We successfully applied molecular markers to estimate relatedness between individuals and access the extent of clonal diversity and genetic flux between phonologically isolated genotypes. Work is ongoing to determine the drivers of trait variation, to combine phenotypic variation and relatedness to determine trait heritability and to understand the genetic basis of adaptation. The heritability estimates will be used in conjunction with genetic correlations and selection coefficients to calculate adaptive potential in S. herbacea. 15. Reiko Akiyama Adaptive significance of allopolyploids in Cardamine Allopolyploidy is pervasive in plants, but little is known about the molecular mechanism of adaptive significance of allopolyploids. The chance of survival of an allopolyploid is likely to be increased by ecological divergence from the progenitors. The genus Cardamine offers an excellent system to study adaptive significance of allopolyploidy. Cardamine flexuosa is an allotetraploid originated between a wet-­‐habitat species C. amara and a dry-­‐habitat species C. hirsuta. The allopolyploidisation occurred independently at least 10 times. Greenhouse experiments have shown that C. hirsuta is tolerant to drought but intolerant to submergence, while the opposite is true to C. amara, and C. flexuosa shows no difference in tolerance to drought and submergence. Microarray analyses indicated that gene expression of C. flexuosa mimics the advantageous pattern of either parent. These findings suggest that the polyploidy adapts to the novel fluctuating habitat by exploiting the genes necessary for survival in both wet and dry habitats. However, there is yet no study quantifying water availability, life history and transcriptomics of these Cardamine species in field, and thus how the findings under controlled conditions relate to the field ones remains to be known. In a sympatric habitat in Switzerland, we will examine whether the water availability in the habitat throughout the growing season is related to (1) survival, growth, and fecundity, and (2) expression of candidate genes for stress tolerance of C. flexuosa, C. amara, and C. hirsuta, and determine whether C. flexuosa diverges from C. amara and C. hirsute. 16. Chow Lih Yew Evolutionary genomic studies of self-­‐compatibility in Arabidopsis kamchatica The genetic basis of the evolutionary transition from outcrossing to selfing has been a major focus in evolutionary biology. Selfing, most commonly, evolved through the breakdown of the self-­‐incompatibility (SI) system that consists of the male specificity component, the S-­‐locus cysteine-­‐rich protein (SCR), the female specificity component, the S-­‐locus receptor kinase (SRK) and genes that involve in downstream signaling pathway. SCR, a small cysteine-­‐rich protein, expresses at the pollen coat and acts as the ligand of SRK, a transmembrane serine/threonine receptor kinase that expresses on the stigma. Interaction between SCR and SRK from the same S-­‐haplogroup triggers downstream mechanism to inhibit pollen tube germination on the stigma. My PhD project focuses on the evolution of self-­‐
compatibility (SC) in Arabidopsis kamchatica. It is a selfing tetraploid species, originated through allopolyploidization of multiple individuals from two diploid species, Arabidopsis halleri and Arabidopsis lyrata that are predominantly outcrossing. Five SRK haplogroups have been identified in Arabidopsis kamchatica. Interpecific crosses with its parental species, Arabidopsis halleri showed that SRK and genes involved in downstream signaling pathway are still functional in some accessions, while no functional SCR has been identified. This suggests that mutation in the male component, SCR is responsible for the loss of SI in Arabidopsis kamchatica. However, the isolation of SCR through conventional PCR method has been difficult due to its short and highly polymorphic sequences. Therefore, next-­‐generation sequencing has been exploited for the isolation of SCR to unveil the evolution of SC in Arabidopsis kamchatica. 19
17. Katherine Horgan The role of parasitism in urabn pollinator communities. The adundance, species richness and eveness of reed nesting Hymenoptera in Family Gardens in Zurich were measured in a 2011 Masters study. Now the collected specimens are being further analysed to see how the structure of the interactions, or food webs, between species differ across the targeted gardens. This work looks at how healthy these insect communities are and whether foodwebs with more species and more interactions are more resilient to disturbance and parasitism. In highly disturbed habitats, such as gardens and particularly gardens in an urban environment, Hymenoptera populations become vulnerable. Low numbers of solitary bees and wasps leads to a resulting loss of the valuable pollination services they provide. This work is intended to add to the understanding of how existing gardens could be managed to maximize Hymenoptera populations and their connected community biodiversity. The study will also examine how the data fits current food web models. 18. Sarah Pellkofer The effects of local and landscape-­‐level characteristics on the abundance and diversity of solitary-­‐nesting Hymenoptera in urban family gardens. Urbanization has been increasingly transforming natural areas into city landscapes dominated by man-­‐made infrastructure. Family gardens (Areas) are one component of this urban landscape that could act as essential habitat to species of solitary-­‐nesting Hymenoptera that still remain within the city, however, many of these gardens have been facing increased pressure to be closed and developed. As the ecosystem services of pollination and pest control that these Hymenoptera provide are extremely valuable to humans, this study sought to determine if these gardens are truly a habitat for solitary-­‐nesting Hymenoptera within the city of Zurich and also what features of these gardens on the local and landscape scale make them more suitable as such a habitat. Using trap-­‐nests this study analyzed how strongly a) abundance, b) richness and c) evenness were predicted by three landscape-­‐level variables and three local-­‐level variables. The landscape-­‐level variables examined were 1) Area size, 2) the greenness of the Area surroundings and 3) the Area’s daily potential solar radiation and the local-­‐level variables were 4) the use of pesticides, 5) the number of existing nesting sites, and 6) the ground cover diversity within individually managed garden plots in each Area. The results of this study showed that on the landscape-­‐level Areas that were smaller with greener surroundings had increased abundance and richness of hymenopteran genera. Areas that were smaller also had increased evenness among those genera. Daily potential solar radiation was not an effective predictor of the abundance, richness and evenness of solitary-­‐nesting Hymenoptera. On the local-­‐level, garden plots with lower ground cover diversity had a higher abundance of hymenopteran genera; however, it was not a predictor the richness and evenness of the genera. Furthermore, the number of existing nesting sites and the use of pesticides were not effective predictors of the abundance, richness and evenness of solitary-­‐nesting Hymenoptera. Although the findings of this study were not in line with many of the original hypotheses, the larger finding that there are a great number of hymenopteran individuals and moreover a wide variety of genera utilizing these family gardens within all varieties of gardens analyzed, it can be said that these family gardens are an important habitat for these species. Therefore, the value of the ecosystem services provided by the species utilizing these gardens should be taken into account when determining the best future use for the urban land currently occupied by family gardens in the city of Zurich. 19. Masaomi Hatakeyama Ecological Genomic Study of Arabidopsis halleri subsp. Gemmifera We study the evolution of Arabidopsis halleri subsp. gemmifera from the viewpoint of ecological genomics. The individuals are taken from several populations across Japan focusing on the relationship between gene variation and heavy-­‐metal pollution. Some of the populations are known to be located on old mines in Japan. We use parallel tagged sequencing method on the 454 platform proposed by Meyer et al., in which each individual is assigned using a unique sequence tag ligated to PCR products. The sequence data were assembled and mapped by using CLC Cell Assembly. As a result, we determined haplotypes of 18 genes. The criteria for determining haplotypes based on low-­‐coverage data are as follows: 1. One haplotype is determined for each diploid individual, 2. Insertion and deletion are ignored, 3. Nucleotide sites that are supported by at least two reads are used for obtaining a consensus sequence for each individual. We have found that heavy-­‐metal related genes have low polymorphism in the three populations from the areas of old mine. We plan to analyze the population structure and demographic history, and to detect a signature of natural selection on target genes with a coalescent simulation incorporating estimated demography parameters. 20
20. Maan Rokaya Rheum acuminatum and Rheum australe: Do they differ from one another? Use of medicinal plants is traced back to the Vedic period in Indian subcontinent. To develop sustainable harvesting strategy for the Himalayan rhubarbs (Rheum acuminatum and Rheum australe), we studied their demography, and also the concentration of different phytochemicals (chrysophanol, emodin, aloe-­‐emodin, piceatannol, physcion, rhein, and resveratrol) in cultivated and naturally grown plants. We also used simulation techniques to assess the effects of harvesting on performance of the species. The asymptotic growth rates (λ) for 0.5 % seed germination rate varied from 1.02-­‐ 1.09 for R. acuminatum growing in forest habitats, 0.87-­‐1.05 for R. acuminatum growing in open habitats and 1.03-­‐
1.17 for R. australe growing in open habitat. R. acuminatum population in open habitat was more vulnerable to harvesting than the populations in forest or of R. australe. The populations decline under all types of harvesting except for 25 % harvest for every year or higher levels of harvests carried out every 3 or more years for R. acuminatum in the forest or in the open habitat. Aloe-­‐emodin and rhein were nearly absent in cultivated roots of both species, and the concentrations of emodin, physcion and chrysophanol were slightly higher in roots from natural habitats than from cultivated sites. Piceatannol and resveratrol were present in almost the same amount in cultivated and natural samples from both species. It is thus concluded that there should be selective or rotational harvesting of both Rheum species and two species could be used interchangeably for medicine. 21. Jitka Klimesova Growth of the alpine clonal herb over two decades: coupling with climatic signals Herbaceous plants, unlike trees, are predicted to react less sensitively to climate changes because their compact canopies attached to the ground are not coupled with ambient air conditions. Using morphological markers preserved on rhizomes, we tested this prediction for Rumex alpinus in alpine zone of Low Tatra Mts., West Carpathians. Since the impact of climate on plant performance in alpine conditions can be modified by the strong micro-­‐topographically induced variation in snowpack duration, and hence a growing season length, we analyzed growth responses for snowbed and control plants during two decades (1977-­‐1988 and 2001-­‐2010). These differed by average summer temperatures (being about 2 K warmer during the last decade) but had the same length of season and sum of precipitations. The snow accumulation shortened growing season for the plants in the first decade, thus climatic events causing further season shortening reduced plant vegetative growth (high precipitation in previous October and current April) whereas events causing prolonging of growing season (warm September) supported plant growth in snowbed site. While snowbed plants were more affected by actual weather, plants from outside of snowbed were more dependent on preceding year weather. In the second, warmer decade the length of season became non-­‐significant for plant performance and August temperatures had the principal positive effect on number of leaves and rhizome increment both in snowbed and control site. Our study shows that growth of herbs similarly like trees is closely coupled with climatic signals and the responses are modified by topography on small scale. 22. Daniel Prati Species traits rather than site characteristics determine establishment success in grasslands as revealed by a broad scale seed addition experiment Dispersal-­‐ and seed limitation are known as influential processes limiting species richness especially grassland ecosystems with transient seed banks. Understanding the factors influencing dispersal limitation in plants is important in particular for restoration ecologists who want to increase local diversity and because of its consequences on ecosystem processes. Within the framework of the Biodiversity Exploratory Project we tested for dispersal limitation by adding seeds from the local species pool to 85 grassland locations across two regions in Germany which differed widely in land use, soil conditions, productivity and resident species richness. We added about 60 species from the regional species pool covering a range of functional trait combinations to each of the grasslands. Three years after sowing we found an establishment success of plots (the proportion of new species per plot) of 7 % across all grasslands, ranging from 0 % to 34 %. The establishment success of plots varied between regions but was independent of resident species richness, productivity, or land use. Instead, we found that establishment success of species depended on their traits: higher seed mass, lower vegetative spread, and lower leaf mass resulted in higher establishment rates. Our study clearly shows that dispersal-­‐ and seed limitation can generally limit local species richness in fragmented cultural landscapes. Successful augmentation of local diversity depends much more on species rather than site characteristics, therefore a careful selection of plant species according to their traits is critical for restoring deteriorated grasslands. 21
23. Filip Vandelook Local and regional differences in seed traits of Geranium robertianum L. Geranium robertianum L. is an annual or biennial herb growing in very diverse habitats ranging from railroad tracks and walls to forest edges and open forests. Geranium robertianum has a particular germination strategy, as seeds dispersed to open habitats mainly germinate in summer, while seeds dispersed to more shady habitats germinated mainly in spring. Germination cueing of Geranium robertianum is regulated by two dormancy mechanisms. First, physical dormancy, i.e. a seed coat impermeable to water, has to be broken and secondly there is a physiological dormancy in the embryo which determines the temperature conditions suitable for germination. We designed an experiment to test for local (open habitat vs shaded habitats) and regional (Belgium vs Hessen, Germany) differences in dormancy and seed size of Geranium robertianum. We tested the hypotheses that (1) seeds from plants in open habitats have a stronger physical dormancy, resulting in more bet-­‐hedging (2) seeds from plants growing in shaded habitats are larger (3) seeds sampled in Belgium require less cold stratification to germinate as compared to seeds from the more continental Hessen. We sampled seeds from 17 populations distributed almost equally across open and shaded habitats in Belgium and Hessen. A series of lab experiments and experiments in natural conditions was performed to test our hypotheses. 24. Johannes Heinze Soilfeedback Hypothesis: species with large biomass that are locally not dominant are most strongly limited by negative soil feedbacks. 25. Anna T. Liebaug Variation in vegetation structure and biodiversity in native and invasive Lythrum salicaria populations Most plant communities are dynamic depending on disturbance, species regeneration and growth. The specific neighborhood to which species may adapt is under continuous change. Thus, mean values of vegetation structure and biodiversity may not be particularly informative. We suggest variation in vegetation structure and biodiversity as a new measure for characterizing differences in the selection regime of plant communities comparing sites and regions. Especially, colonizing species might have difficulties in adapting to vegetation structures which are highly variable in time and space. Additionally, invasive species might themself be highly variable in abundance and distribution due to dynamic interactions with e.g. new herbivores, competitors and soil factors. One example of a plant species showing marked heterogeneity in abundances in its invaded range is Lythrum salicaria in North America (Lavoie 2010, Biological Invasions 12: 1967–1999). In this study we want to prove that (1) variation of vegetation structure and species diversity are higher in invaded than in native populations of L. salicaria, and (2) variation in fecundity of L. salicaria is higher in invading populations. Vegetation structure and biodiversity of 100 field sites with L. salicaria in two regions within the native range (Europe) and two within the invaded range (North America) were sampled. Data on L. salicaria fecundity, horizontal and vertical vegetation structure as well as diversity were collected. Results suggest higher variation in vegetation structure as well as in L. salicaria performance in the invaded regions compared to native regions. 26. Andreas Stampfli Is semi-­‐natural grassland resilient to extreme drought? Can management be adapted to avoid undesirable impact? Coauthor: Michaela Zeiter Important change in ecosystems may originate from chance effects of climate and land use interacting through the process of plant regeneration. Resilience is the capacity of an ecosystem to absorb disturbance by undergoing changes in species abundance and diversity while maintaining essential ecological functions. We assess resilience in a field experiment by integrating plant processes over four years after extreme-­‐drought and seed-­‐addition treatments. We ask: (1) Do droughts cause species losses by mortality and create opportunities for new recruits? (2) Is invasibility affected by drought, and are effects modulated by neighbourhood-­‐scale species richness of the extant community? (3) Do seed scarcity due to agricultural management and extreme droughts affect productivity and species richness by way of changing vegetation structure? Rainwater was reduced in summer and spring and added to the control. Rainwater reduction desiccated the soil and strongly reduced phytomass in the subsequent seasonal harvest. Current haymaking was maintained with or without 22
regular addition of seeds of ten local species (6250 seeds/m2). Species frequency was annually recorded in July, separately for established plants and recruits, starting before experimental treatments. Phytomass was measured in June until year five. Low mortality of the resident species translated into high community resilience. Recruitment of the resident species after drought was poor. Invasibility was positively related to species richness of residents at the neighbourhood scale but summer drought neutralized this relationship indicating that diversity-­‐related processes were deactivated. Unaffected invasibility after extreme drought adds to the stability, while a deficient supply of seeds contributes to a gradual transformation of this species-­‐rich grassland. 27. Juliane Preukschas Seed predation in Swiss semi-­‐natural grasslands Seed availability and seedling establishment play an important role in the regeneration of grassland ecosystems. Seed predation may strongly affect propagule pressure, one of several factors that determine the recruitment of species. Seed predation may vary according to aspects of the locality, such as density of seeds and species richness. Seed predators may select species according to seed size and prefer seeds of species which occur in their home range. We performed a seed-­‐predation study in seven grassland localities across Switzerland, over an annual-­‐productivity range of 130-­‐750 g/m². We offered seeds of 36 temperate-­‐grassland species, 18 indigenous species from Switzerland and 18 non-­‐indigenous species from the North-­‐American prairie. The seed-­‐weight range was 0.13-­‐6.80 mg. In summer 2011 seeds were offered in petri-­‐dishes which were filled with sterilized soil and were placed level with the soil surface. After three days, totally 216 petri-­‐dishes per locality were collected and the remaining seeds were counted. Preliminary results indicate a high variability in seed predation between localities and species, but no clear difference between indigenous and non-­‐indigenous species. 28. Jennifer Williams The role of density dependence in populations spreading through patchy landscapes Predicting how an invasive species will spread through a new landscape or how a native species will expand its range with climate change requires understanding the speed at which species move across landscapes. Much of our current understanding of spread comes from theoretical models that treat landscapes as uniformly favorable environments. However, real landscapes are mosaics of suitable and unsuitable habitat. Recent models predict that gaps between suitable habitat can fundamentally change how invasions advance. In contrast to continuous landscapes, where rare individuals at the front drive populations forward, spread in patchy landscapes is suggested to be driven by individuals growing at high density. Here we combine empirical work with theoretical models to more closely examine the role and mechanisms by which density dependence drives spread in patchy landscapes. We show that in a model system of the annual plant Arabidopsis thaliana (thale cress), the dispersal kernel is highly influenced by plant density. With integro-­‐
difference equation models of population spread, we then show how different forms of density dependence, including its influence on the dispersal kernel, affect the spread velocity. 29. Zuzana Munzbergova Effects of genetic diversity within a species on stand resistance to invasion Coauthors: Věra Hadincová, Hana Skálová While effects of species diversity on a wide range of ecosystem functions have been repeatedly demonstrated, the effects of genetic diversity within species are still relatively little explored. Previously, we created monospecific stands of a dominant grass species, Festuca rubra, consisting of 1, 6 or 18 different genotypes sampled from mountain grassland and tested the effects of genetic diversity on stand productivity. We demonstrated higher productivity in more genetically diverse stands in the 1styear of the experiment, but not later. Here, we explore the effect of genetic diversity within these stands on their resistance to invasion of new species. Specifically, we have sown 4 grassland species commonly occurring with F. rubra into the stands and followed their fate as well as their effect on F. rubra. The results showed that stands of higher genetic diversity were more resistant to invasion by the new species. The effects of genetic diversity on performance of the new species were stronger in the 23
early stages of development of the new species. The effects of genetic diversity of F. rubra stands were significant even after using biomass of the F. rubra stands as a covariate. This indicates that genetic diversity of F. rubra stands has additional effects on performance of the new species than only effects related to higher biomass production of these stands. In addition, we also showed that the biomass of F. rubra stands was suppressed less by the newly invading species when the stands had higher genetic diversity. 30. Zuzana Munzbergova Relationship between species traits and habitat occupancy differs among species with different patterns of distribution Coauthor: Lucie Hemrová Fast recent landscape changes have initiated discussion on plant species dynamics in agricultural landscape. Although habitat occupancy has been repeatedly shown to depend on species dispersal and/or growth related traits, the patterns largely vary among studies. We hypothesize that this variation may be caused by different distributional patterns of different species. We identified occupancy of suitable habitats for 99 dry grasslands species in 60 km2 landscape. The species were divided according to their frequency on suitable habitats and rarity of the suitable habitats in the landscape into three groups: common species (frequent on common habitats), medium-­‐rare species (frequent on rare habitats) and rare species (rare on rare habitats). We tested the relationship between dispersal and growth related traits and habitat occupancy among all species and within individual groups. The analyses were performed with and without phylogenetic correction. Habitat occupancy depended on the number of suitable habitats in the landscape. The habitat occupancies within species of particular groups were explained by different traits. For example, endozoochory had no effect on habitat occupancy of the common species, positive effect in medium-­‐rare species and negative effect in rare species. Seed mass had positive effect in common species, no effect in the medium-­‐rare species and negative effect in the rare species. Our results suggest that different traits can explain the occurrence of species with different distributional patterns. Therefore, the type of distributional pattern should be considered when searching for the relationship between species traits and habitat occupancy. 31. Vit Latzel Adaptive transgenerational modification of biomass and storages in a perennial plant Phenotypic variation in plants has been a focus of interest for ecologists and evolutionary biologists for many years. While some of this variation directly reflects differences among genotypes, some of it represents adaptive phenotypic plasticity, in which plants adjust their phenotypes in response to biotic and abiotic differences. In recent decades it has also been shown that the phenotype expressed by an individual can be affected by the environment experienced by the parental generation. Such transgenerational effects have great ecological and evolutionary relevance because they can affect the degree of adaptive plasticity. In our study we tested whether transgenerational effects may alter adaptive response of progeny to changing nutrient availability in a perennial Plantago lanceolata. In particular, we tested the role of maternal effects in the degree of adaptive change in biomass production and storages management in differently productive environments. Plants of progeny generation produced significantly more biomass and more storages if were grown in maternal than non-­‐maternal nutrient conditions. Moreover, such adaptive transgenerational plasticity was independent on genetic variation and on time period of progeny origin. We conclude that maternal effects are adaptive in P. lanceolata playing thus important role in ecology and microevolution of the species. We also conclude that maternal effects can affect competitive ability, fecundity or stress tolerance of perennials by transgenerational alteration of their storage management. 32. Kentaro Shimizu Toward recurrent patterns in the evolution of selfing Ever since Darwin’s pioneering research, the evolutionary transition from obligate outcrossing to predominant self-­‐
fertilization (selfing) has been regarded as one of the most prevalent events in flowering plants. A major mechanism to prevent selfing is the self-­‐incompatibility (SI) recognition system. Under conditions that favor selfing, mutations disabling the male recognition component are predicted to spread faster than those disabling the female component, because male mutations can be transmitted by both pollen and seeds, whereas female mutations can be transmitted increase only through seeds. We found similar patterns in the diploid A. thaliana and the allotetraploid A. kamchatica 24
(derived from diploid A. lyrata and A. halleri). Crossing and transgenic experiments showed that female components of SI including female specificity gene SRK are still functional in many accessions in both species, while male components are non-­‐functional. The distribution of S-­‐locus haplogroups deviated from genome-­‐wide pattern in both species. In addition, divergence of low-­‐copy genes and transposable elements suggested that the evolution of predominant selfing occurred recently, coinciding with glacial-­‐interglacial cycles. Our compilation and statistical analysis of recent extensive studies in multiple Brassicaceae species demonstrate that, in contrast to cultivated species, the loss of SI tends to be derived from mutations in the male component in wild species. 33. Gerhard Karrer Can Post-­‐harvest Ripening of Seeds hamper the Efficacy of Control Measures against Common Ragweed? The invasive annual plant Ambrosia artemisiifolia L. (Common ragweed) started to spread in Austria massively around 1980. Besides agricultural fields, road shoulders turned out to be favourable habitats for establishment and further spread. Machines used for mowing the shoulders and batters along any roads contribute most to the spread of ragweed. Common practice of control at such habitat types is mowing or mulching few times a year thereby leaving the biomass. In a cutting experiment we tried to quantify the post ripening potential of flowers/young seeds from branches cut at different developmental stages of the female flowers. All cut material was left at the ground for post-­‐harvest ripening until end of autumn. The seeds gained from the experiments were tested regarding their germination capacity and dormancy/viability (Tetrazolium-­‐test). Indeed, the post-­‐harvest ripening potential was high in common ragweed. Seeds developed from inflorescences that were harvested at the beginning of September showed germination rates of 25 to 50 %. Thus it is evident that cut Ragweed-­‐biomass must be removed from the road shoulders after mowing to prevent ripened seeds from further spread and filling up the soil seed bank. 34. Mialy Razanajatovo Pollinator visitation of native and alien plant species Organisms can only persist in their current regions and colonize new regions if they manage to reproduce. More than 80% of plant species rely, at least partly, on pollinators for reproduction. Therefore, it is surprising that many alien plant species -­‐ in the absence of their usual pollinators -­‐ manage to reproduce and become invasive in new regions, where they can impose serious threats to native biodiversity and local economies. Recent studies have shown that invasive alien species have managed to integrate themselves well into native plant-­‐pollinator webs. However, it is not known whether alien species that did not establish naturalized populations are less successful in attracting pollinators. Therefore, to test whether native and naturalized and non-­‐naturalized alien plants differ in pollinator visitation rates, we conducted a multispecies comparative study of pollinator visitation of native and alien plant species in the Botanical Garden of Bern. Overall, pollinator visitation to native and alien species did not differ. However, pollinator visitation was lower to non-­‐
naturalized alien species than to naturalized and native species. These results indicate that the capacity of naturalized alien plant species to attract native pollinators might have helped them to establish and become invasive. 35. Lisanna Schmidt Diversity and morphological variation in the Carex flava complex (Cyperaceae) Assessing morphological differentiation and allozyme variation in the Carex flava complex (C. flava, C. lepidocarpa, C. demissa and C. viridula s.l.) was the main goal of this survey. Although molecular data are useful for elucidating phylogenetic relationships between critical groups, it is also important to consider morphology. To evaluate morphological differentiation in C. flava complex, 179 specimens from herbaria were used. It can be said that there is no single character that discriminate taxa perfectly, several variables must be considered. Although individual plants exhibit certain combinations of characters that make them appear quite distinctive, these characters do not covary concsistently and taxa can be delimited only using combination of characters. Reproductive features express less variability than vegetative so preferably they should be used. It is suggested to use perigynia in the middle of pistillate spiklets. For evaluating genetic diversity and describing the breeding mode, allozyme analysis were conducted on 13 Saaremaa populations (1 of C. flava, 8 of C. viridula var. viridula and 4 of C. viridula var. pulchella). A total of 8 polymorphic loci were used. The overall genetic diversity was higher in C. viridula var. viridula. Estimated values of fixation index (F) and outcrossng rate (t) indicated substantial allogamy in C. flava, and almost total autogamy in C. viridula var. viridula and C. viridula var. pulchella. Estimates of genetic diversity found in the present study are similar to those reported by other 25
investigators; the allozyme data demonstrate increasing genetic variability with increasing r-­‐selection (C. viridula var. viridula). Carex viridula var. viridula specific allozymes at three loci (EST-­‐B, SOD-­‐A and 6PGD-­‐A) were also found in the present study. These data support recognition of C. viridula var. viridula as a distinct taxon from C. viridula var. pulchella and C. flava. 26